posted by Anonymous .
The rocket coaster has 15 cars, some that hold 4 people and some that hold 6 people. There is a room for 72 people altogether. How many 4 passenger cars are there? How many 6 passenger cars are there?
let the number of 4-people cars be x
then the number of 6-person cars is 15-x
4x + 6(15-x) = 72
4x + 90 - 6x = 72
-2x = -18
x = 9
9 of the 4-person cars and 6 of the 6-person cars